Molding composition



Patented May 14, 1 940 1 UNITED STATES I 2,201,028 ,L'MOLDINGCOMPOSITION David E. Cordier, Toledo, Ohio, assignor to Plaskon Company,Incorporated, Toledo, Ohio, a corporation of Delaware No Drawing.

Application September 28, 1938,

Serial No 232,225

5 Claims.

, The invention is plasticized formaldehyde-urea molding compositions.

Formaldehyde-urea molding compositions are thermosetting, i. e., whenmolded under elevated pressure" and temperature they first soften andthen harden at the molding temperature. A thermoplastic moldingcomposition, in contrast, remains soft until the molded article hascooled. Although an article molded from a thermosetting composition canbe removed from the mold after a relatively short time and while thearticle is still hot, an article molded from a thermoplastic compositioncannot be removed from the mold until it has cooled, and thus'harden'edsufiiciently so that it does not become blistered or distorted uponrelease of the pressure. The length of time for which a moldingcomposition must be left in the mold is one of the factors thatdetermines the cost of articles molded from the composition. Acomposition that must be left in the mold twice as long as anothercomposition requires about twice as much molding equipment for the samevolume of production, and hot-molding equipment is expensive,

Although the thermosetting character of formaldehyde-urea moldingcompositions is highly advantageous, the softening of such compositionsthat occurs in the mold before setting or hardening takes place is veryimportant. A thermoset ting composition that does not undergo properinitial softening in the mold cannot be molded properly. For example, anarticle molded from such a composition may not be properly homogeneous,and may consist of incompletely softened granules cemented together.Granular, unfused structure, due to insufficient softening of thecomposition in the mold, is found most frequently in the centralportions of relatively thick articles, such as knobs and handles.

Insuflicient initial fusing results in an unhomogeneous appearance ofthe finished article, such as a streaked surface in the case of acolored article. The surface appearance that is produced by failure of amolding composition to soften before setting is known as dog.skin. Whena molding composition does not soften sufficiently in the mold, bubblesor pockets of gas are frequently trapped, and produce flaws in thefinished article.

Although acid substances have been used as plasticizers informaldehyde-urea molding compositions containing no cellulose, suchsubstances cannot be used in a composition containing cellulose as afiller, because they render it unstable and cause rapid deterioration.Formaldehyde urea molding compositions containing no cellulose have notbeen found satisfactory for commercial use.

To be suitable for use as a plasticizer, a substance should not be' soalkaline as to prevent the formaldehyde-urea molding composition fromhardening in the mold. Substances that are highly soluble in Watercannot be used as plasticizers, because they seriously impair theresistant properties of a formaldehyde-urea resin. I

Phenol has been suggested as a plasticizer for formaldehyde-urea moldingcompositions, but it is unsatisfactory because it imparts an undesirablecolor and odor to the compositions. Moreover, the color of aformaldehyde-urea composition containing phenol is so unstable that thecomposition would have to be handled in a re- I frigerated dark room toprevent the appearance of the molded articles frombeing spoiled. Toluenesulfonamides have been used for want of better plasticizers, but theirplasticizing efiect is so slight that they are of little value.

Only substances that are soluble in formaldehyde-urea resin can be usedas plasticizers, because insoluble substances bleed out of the resin andthus spoil molded articles in which they are used. The substances thatare soluble in formaldehyde-urea resin are very limited in number. Mostof such substances seem to have a molecular structure similar to that ofthe resin; for example, certain urea derivatives are soluble informaldehyde-urea resin. However, urea derivatives in general do nothave a plasticizing effect upon formaldehyde-urea molding compositions.Urea itself cannot be used as a plasticizer because of its deleteriouseffect upon the product. The substances that are both soluble informaldehyde-urea resin and capable of appreciably plasticizing aformaldehyde-urea molding composition are extremely rare. The principalobject of the inventionis to provide formaldehyde-urea moldingcompositions containing novel plasticizers. More specific objects andadvantages are apparent from the description, which merely discloses andillustrates molded from the composition.

limitations upon the claims.

A molding composition embodying the invention contains a plasticizerselected from the group consisting of organic compounds of the generalformula Y is hydroxyethyl, hydroxypropyl, hydroxybutyl or hydroxyamyl,and Z is H or Y.

Plasticizers illustrative of the general formula 0 R-(.-eH4-SX are (l)N, p-toluenesulfonyl ethanolamine and N, o-toluenesulfonyl ethanolamine(2) N, p-toluenesulfonyl diethanolamine'and N, o-toluenesulfonyldiethanolamine and (3) N, N '-di-p-toluenesulfonyl ethylene diamine aa"CHrCH4SNHCHrCHr-NHSCaH4-CH3 0 0 Compounds (1) are somewhat soluble inwater, but their use in a molding composition only slightly decreasesthe water resistance of articles A formaldehyde-urea molding compositionof the usual type, consisting primarily of cellulosic material (40 to50%)' and a formaldehyde-urea reaction product, may be employed.

Example A dried formaldehyde-urea molding composition containing partsof alpha-cellulose fiber impregnated with 50 parts of a formaldehydeureareaction product is ground in a ball mill, together with 51 parts ofN,N'-di-p-toluenesulfonyl ethylene' diamine. The customary modifiers.such as lubricants, accelerators, and coloring matter, may also be addedto the ball mill. After an intimate mixture has been obtained in theform of a fine powder, it may be granulated or formed into pellets sothat it can be used conveniently for charging molds. The molding is theinvention and is not intended to impose performed under a suitablepressure at a temperature of about 150 C.

Various applications of the invention may be devised to meet variousrequirements.

Having described my invention, I claim:

1. A thermosetting molding composition comprising a formaldehyde-ureareaction product and a plasticizer selected from the group consisting oforganic compounds of the general for-.

mula

in which R is a member of the group consisting of H and CHaX is a memberof the group consisting of Y is a member of the group consisting'oihydroxyethyl, hydroxypropyl, hydroxybutyl and hydroxyamyl, and Z is amember of the group consisting of H, hydroxyethyl, hydroxypropyl,hydroxybutyl and hydroxyamyl.

2. A formaldehyde-urea molding composition comprising aformaldehyde-urea reaction product, cellulosic material, and aplasticizer selected from the group consisting of organic compounds ofthe general formula 0 RCcH4-SX in which R- is a member of the groupconsisting of H and CH X is a member of the group consisting mwm E.CORDIER.

mscLAmER 2,20 1 ,028.-'-David E. Oordier, Toledo, Ohio. MOLDIiNGCOMPOSITION-'- Patcnt dated.

[Oficial Gazette December 2, 1941;]

filed November 5, 1941, by the formaldehyde-urea reaction proddo-ureamolding compositions which said'plasticizer is N,p-toluene sulfonylethanolamne;

assignes, Plaskon further disclaims from claim'1all ulosic material anda plasticiaer,

